docstr: Remove the views associated with the client when the websocket
  closes.
docstr_tok: ["Remove","the","views","associated","with","the","client","when","the","websocket","closes","."]
code: def on_close(self):
      """Remove the views associated with the client when the websocket
      closes.
      """
      self._session.close()
  
file_path: perspective/python/perspective/perspective/handlers/common.py
imports: import asyncio
  from abc import ABC, abstractmethod
  import functools
  from ..core.exception import PerspectiveError
label_desc: Use image node_id 4 for calling the PerspectiveHandlerBase obj's underlying member method code with example usage: obj.on_close() without return types